Difficult economic conditions have forced the New Zealand Aluminium Smelter (NZAS) to pull out of a landmark conservation programme.
NZAS had sponsored the kākāpō recovery programme for 25 years at a cost of $4.5 million, but said it could no longer afford it.
The programme had helped kākāpō numbers rise from 49 to 125.
The smelter said it served notice in 2003 that market conditions meant continued sponsorship was unlikely.
The company managed to extend its programme for another 12 years, but last year told the Department of Conservation (DoC) of its intention to quit.
NZAS said, in 1990, it earned $4545 for each tonne of aluminium it produced but today it was getting $2250 per tonne.
The drop in price meant the smelter was almost closed two years ago, but it received government assistance to stay open.
However, management has not ruled out the option of closing in 2019.